Source detection apparatus and method for audience measurement

ABSTRACT

Apparatus, methods and articles of manufacture for determining an operating mode of a recording/playing device are disclosed. An example apparatus includes an extractor to extract signatures associated with a first signal associated with a tuner that is to tune to a program signal, a second signal associated with a recording/playing device that is to at least one of record and play a program, and a third signal associated with a receiver coupled to the recording/playing device. The example apparatus also includes a recording detector to detect a recording signal generated by the recording/playing device during recording of the program to form a recorded program. Also included is a correlator to correlate the first, second, and third signals and a processor to identify the operating mode of the recording/playing device based on detection of the recording signal and correlation of two or more of the first, second, and third signals.

RELATED APPLICATIONS

This patent claims priority to U.S. patent application Ser. No.12/823,374, entitled “Source Detection Apparatus and Method for AudienceMeasurement,” filed on Jun. 25, 2010, which claims priority to U.S.patent application Ser. No. 10/693,549, entitled “Source DetectionApparatus and Method for Audience Measurement,” filed on Oct. 24, 2003,which claims priority to U.S. patent application Ser. No. 08/786,270,which issued as U.S. Pat. No. 6,675,383, entitled “Source DetectionApparatus and Method for Audience Measurement,” filed on Jan. 22, 1997,all of which are hereby incorporated by reference in their entireties.

FIELD OF INVENTION

The invention relates to the field of television audience research, andmore particularly, to the detection of the viewing of television signalsoriginating from a signal source within a statistically sampledhousehold.

DESCRIPTION OF PRIOR ART

As disclosed by Thomas et al., in U.S. Pat. No. 5,481,294, which isassigned to the same assignee as the present invention and thedisclosure of which is herein incorporated by reference, the signal(i.e., television or radio), that has been selected, and is being viewedor heard, by an audience member on a television or radio receiver in astatistically selected household, may be determined by ascertaining thechannel to which the tuner of the television or radio is tuned. Thischannel information is stored locally for subsequent retrieval by acentral data collection office. The central data collection officematches the retrieved channel information against a cable/station recordwhich indicates which station corresponds to which channel and/oragainst a program record list of television or radio programs which weretransmitted on that channel in order to determine the television orradio program that the audience member selected. As noted in U.S. Pat.No. 5,481,294 by Thomas et al., this process becomes cumbersome as thenumber of signal sources, the number of channels, the changes to channelmappings at a cable head-end, and/or the number of television or radioprograms increase, and can fail to produce usable data if there is anerror in the program record list that provides the concordance betweenchannels and programs.

Several approaches have been proposed that are intended to avoid thecumbersome cable/station record and/or program record list manner ofkeeping track of which station and/or which programming is availablefrom which signal source and channel within a sampled household. As anexample, one such approach has employed a program monitoring system thatreads an identifying code embedded in the program, and uses theancillary code to identify the program to which the television or radiowas tuned.

As another example, a program signature is extracted from the programsignal selected for use (i.e., for viewing if the signal is a televisionsignal, or for listening. if the signal is a radio signal) in thesampled household and is later compared to previously extractedreference signatures in an effort to match the program signature to apreviously extracted reference signature in order to thereby 5 identifythe selected program. Accordingly, this signature approach is acorrelation system which uses a sample frequency that is less than thefrequency of the program signal.

Such monitoring equipment in the sampled household also stores a timestamp in addition to the ancillary code or program signature. The timestamp is used to determine the time and date of viewing and/or listeningrelative to the selected program.

Thomas et al., in U.S. Pat. No. 5,425,100, and U.S. Pat. No. 5,526,427,both of which are assigned to the same assignee as the presentinvention, teach a hierarchical, multi-level encoding system foridentifying a transmitted program by reading an ancillary programidentifying code which is sequentially added to the program as it passesthrough various stages of a program distribution network. Thedisclosures of U.S. Pat. No. 5,425,100 and U.S. Pat. No. 5,526,427 arehereby incorporated by reference. Other program monitoring systemsemploying ancillary codes which are embedded in a transmitted programare taught by Hasel-wood et al. in U.S. Pat. No. 4,025,851, and byCrosby in U.S. Pat. No. 3,845,391.

A program monitoring system that exclusively relies on ancillary codesmay produce inaccurate results when ancillary codes are eitherintentionally or accidentally omitted from program signals. Even whenthe original program signal is encoded with an ancillary code, there isa risk that the ancillary code will be intentionally removed before theprogram signal is viewed or heard. There is also the risk that ancillarycodes may be accidentally removed before the program in which they areembedded is viewed or heard. For example, ancillary codes that areembedded in video or audio program signals so that they are undetectableto a viewer or listener, or so that they are at least unobtrusive enoughto be no more than minimally detectable by a viewer or listener, arecommonly stripped from the video or audio program signals when the videoor audio program signals are compressed (e.g., such as by the MPEG IIcompression scheme used with digital television signals).

Moreover, ancillary codes, which are inserted into vertical blankingintervals (VBI) of the video portions of program signals, and whichsurvive passage through the signal transmission chain so as to bereceived by a user's television receiver, are commonly removed from thevideo before the video is applied to the CRT of a television. As aresult, non-intrusive acquisition of these VBI ancillary codes isimpractical because such non-intrusive acquisition usually requires theuse of probes which generally pick up the video sent by the tuner to theCRT after the VBI ancillary codes have already been stripped from thevideo.

Therefore, ancillary codes in the vertical blanking interval are moreeasily detected if the monitored television receiver is opened so thatleads of the monitoring equipment can be soldered to video test pointsof the television receiver at which the ancillary codes are stillpresent. However, such an arrangement is intrusive, leading toobjections by the members of the statistically sampled households.

Signal comparison program monitoring systems, other than signaturematching systems such as those described above, have also been used inorder to determine the signal sources (e.g., channels) of the programsbeing viewed or heard. One of the oldest known signal comparison programmonitoring systems compares a synchronization component of a televisionprogram signal selected by a television tuner with a correspondingsynchronization component in a program signal selected by a referencetuner. This signal comparison program monitoring system credits viewingto the signal source selected by the reference tuner when and if the twosynchronization components match within some predetermined error.

Currey, in U.S. Pat. No. 3,372,233, provided an early teaching of such aprogram monitoring system which compared the phasing of verticalsynchronization signals for this purpose. Currey's approach was notparticularly successful because there are times when thevertical-synchronization components from different signal sourcesoccasionally match. When this type of matching occurs, the programsource measurement is ambiguous. Solar, in U.S. Pat. No. 4,764,808, andGall, in U.S. Pat. No. 4,847,685, provided improved synchronizationcomponent measurement systems that did not entirely overcome the basicshortcoming of the Currey approach. In U.S. Pat. No. 5,294,977, Fisheret al. disclosed a synchronization component based measurement systemoperating in a restricted environment in which such phase coincidencescan be avoided.

Another signal comparison program monitoring system correlates areceiver signal, which may be extracted from a receiver being monitored,with a reference signal, which may be supplied by a reference tuner thatis tuned consecutively to the possible program signal sources to whichthe monitored receiver may be tuned. This correlation system determinesthe channel being viewed or heard when the correlation between thereceiver signal from the monitored receiver and the reference signalfrom the reference tuner exceeds some predetermined value. Thismonitoring approach was initially adapted for the purpose of in-homeidentification of viewed television programs by Kiewit et al. in U.S.Pat. No. 4,697,209, the disclosure of which is herein incorporated byreference. The teachings of Kiewit et al. have been expanded upon byThomas et al., in U.S. Pat. No. 5,481,294, who described the use ofsignatures extracted from either a video component or an audio componentof a receiver signal, and who discussed the operational advantages ofusing non-invasive sensors to acquire the components.

A further comparison program monitoring system was placed in commercialservice in 1984 by the A. C. Nielsen Company and was internally referredto as the Real Time Correlation (RTC) system. The RTC system used acombination of (i) vertical synchronization component matching and (ii)audio correlation in order to identify an unknown signal. The RTC systemdid so by first making a preliminary identification based upon matchingof vertical synchronization components. However, this preliminaryidentification would not be unique if the unknown transmitted signal,for example, was one of several sync-locked signals originating at alocal cable head-end. Therefore, the RTC system resolved ambiguities bycorrelating the audio component of the selected transmitted signal fromthe monitored television with the audio component of the referencesignal from the reference tuner whose synchronization component matchedthe synchronization component of the transmitted signal.

Correlation program monitoring systems are generally more robust andless affected by signal degradation than are code reading programmonitoring systems. Even so, a signal correlation program monitoringsystem, which compares two signals (e.g., a receiver signal selected bya monitored television at a television viewing site in a statisticallysampled household, and a reference signal selected by a reference tunerat a different local reference site), works best when the two signals tobe correlated are both high quality replicas of what was actuallytransmitted. If one of the correlated signals, such as the receiversignal selected by the monitored television, is acquired by anon-intrusive sensor at the television viewing site, and if the othercorrelated signal, such as the reference signal selected by thereference tuner, is acquired from the audio or video circuitry of atuner at a different local reference site, artifacts introduced by thenon-intrusive measurement at the television viewing-site may have asubstantial adverse impact on the correlation between the receiver andreference signals. To reduce such artifacts, Thomas et al., in theaforementioned U.S. Pat. No. 5,481,294, teach the suppression or removalof background noise from an audio signal acquired by a non-intrusivemicrophone at the receiver viewing or listening site.

Another problem facing signal correlation systems is that, becausesignal correlation systems require an ongoing collection of referencesignatures by equipment dedicated to monitoring the signals transmittedfrom each program signal source in whatever regional market is beingmeasured, the operating cost of a signature-based program monitoringsystem is generally higher than that of a comparable program monitoringsystem relying on ancillary codes.

A problem facing all, or nearly all, program monitoring systems arisesfrom signal sources which originate within the household itself. Signalsources of this sort may include computers or video games, which use themonitored television's display, and video cassette (or tape) recorders,which play program signals that were recorded at earlier times or thatare recorded on rental cassettes (or tapes). The use of such localsignal sources is, with one exception to be discussed below,systematically excluded from a long-established audience measurementparameter called “Households Using Television” (HUT) because the use ofa television receiver with a locally generated signal does not fallwithin the scope of conventional television audience measurements.

Moreover, if a local signal source is not identified as such, a programmonitoring system could either (i) erroneously count viewing orlistening based on this local signal source as it would count viewing orlistening based upon a remote signal source, or (ii) label the viewingor listening based on the local signal source as an unidentifiedactivity. Either way, viewing or listening based upon a local signalsource would be included as contributions to the overall HUT valuereported by the program monitoring system in such a way as to createambiguities.

The exception mentioned above relates to recording of programs by VCRsfor later time shifted viewing. The reportable HUT value generallycounts time-shifting viewing either at the time of recording or at thetime of playback, but does not count at both recording and playback. Bynot counting at both recording and playback, double counting is avoided.Also, whether counting is done at the time of recording or at the timeof playback, program monitoring systems strive to count only transmittedprograms and seek to avoid counting non-transmitted programs, such asrented movies.

Also, a VCR typically has a number of modes in a non-record mode. Forexample, in a monitor mode, the VCR is used to pass through a currentlyselected transmitted program signal so that the signal may be viewed ona television, but the VCR does not concurrently record the signal. In atune/record mode, the VCR is used to pass through a currently selectedtransmitted program signal for both viewing and recording. In anon-tune/record mode, the VCR is used to record a program withoutconcurrent viewing of the program on a television; thus, the program isrecorded for time-shifted playing. In a play mode, the VCR is used toplay transmitted materials, and as tune-shifted recordings, andnon-transmitted materials, such as rented movies. In an off mode, theVCR is off. Because of this number of modes, a VCR presents one of themost difficult program monitoring challenges.

Early measurements of VCRs in sampled households involved monitoring ofboth the control switches and the tuners of VCRs. This monitoringresulted in the measurement of recording, which was credited to programratings when recorded, and in the identification of all other uses asnot contributing to program ratings. Thus, for example, when recordingwas counted as HUT viewing, all play activity was counted as non-HUTusage). These early measurements of VCRs involved a complicated andexpensive disassembly and modification of consumers' equipment in orderto physically connect switch monitoring equipment to the VCR switches.

Subsequent improvements in VCR measurement provided less invasive, andin some cases entirely non-invasive, ways of acquiring the requisitesignals. In U.S. Pat. No. 4,633,302, Damoci teaches a method of pickingup an artifact from the output of a VCR's erase-head in order toascertain that the measured VCR is recording a tuned signal. Vitt etal., in U.S. Pat. No. 5,165,069, teach a further improved measurementmethod in which all the status information (including a sensederase-head output, which is commonly selected by different manufacturersto be a continuous wave (CW) tone lying between thirty and seventy-fiveKHz) is acquired from a sensor or pickup located immediately adjacentto, but externally of, the VCR's housing. The disclosure of Vitt et al.is herein incorporated by reference. Mostafa et al., in U.S. Pat. No.5,495,282, teach yet another non-invasive arrangement for monitoring theoperation of a VCR by injecting encoded identification signals into theVCR and searching for that signal in the RF output from the VCR. Yet themonitoring of VCRs continue to be a difficult problem.

The present invention solves one or more of the above-noted problems.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a system foridentifying a signal source supplying a program signal to a monitoredreceiver comprises program signature extracting means and signal sourceidentifying means. The monitored receiver is located in a household. Theprogram signature extracting means extracts a reference programsignature representative of an output of the monitored receiver andextracts a source program signature representative of the program signalsupplied by the signal source. The program signature extracting means islocated in the household. The signal source identifying means identifiesthe signal source as a source of the program signal in response to thereference program signature and the source program signature.

In accordance with another aspect of the present invention, a system foridentifying which of first and second signal sources is supplying aprogram signal to a monitored receiver comprises program signatureextracting means and signal source identifying means. The first andsecond signal sources and the monitored receiver are located in ahousehold. The program signature extracting means extracts a referenceprogram signature representative of an output of the monitored receiverand extracts first and second source program signatures representativeof an output of the first and second signal sources. The programsignature extracting means is located in the household. The signalsource identifying means identifies which of the first and second signalsources is a source of the program signal in response to the referenceprogram signature and the first and second source program signatures.

In accordance with yet another aspect of the present invention, a systemfor identifying a program tuned by a monitored receiver comprises tuningmeans, program signature extracting means, signature correlating means,and code reading means. The monitored receiver is located in ahousehold. The tuning means is separate from a tuner of the monitoredreceiver and tunes to programs tunable by the monitored receiver. Thetuning means is located in a household. The program signature extractingmeans is operably coupled to the monitored receiver and to the tuningmeans, and extracts a first program signature from an output of themonitored receiver and a second program signature from an output of thetuning means. The signature correlating means correlates the first andsecond program signatures. The code reading means is operably coupled tothe tuning means and reads an ancillary code from the output of thetuning means if the signature correlating means detects a match betweenthe first and second program signatures.

In accordance with still another aspect of the present invention, asystem for determining an operating mode of a recording/playing devicecomprises tuning means, first, second, third, and fourth signalacquiring means, and determining means. The recording/playing devicegenerates a recording indicating signal during recording and operates inconjunction with a receiver. The tuning means is separate from a tunerof the receiver and tunes to a program signal. The first signalacquiring means acquires a first signal from an output of therecording/playing device. The second signal acquiring means acquires asecond signal from an output of the tuning means. The third signalacquiring means acquires a third signal from an output of the receiver.The fourth signal acquiring means acquires the recording indicatingsignal. The determining means is coupled to the first, second, third,and fourth signal acquiring means and determines an operating mode ofthe recording/playing device dependent upon the first, second, and thirdsignals and the recording indicating signal.

In accordance with a further aspect of the present invention, a systemfor measuring the use of a video recorder operably connected to atelevision receiver comprises source tuning means, television receiversignal acquiring means, and first and second comparing means. Thetelevision receiver receives a plurality of transmitted televisionsignals. The source tuning means tunes to a source program signalcorresponding to a transmitted television signal. The televisionreceiver signal acquiring means acquires a signal displayed on thetelevision receiver. The first comparing means compares a signal fromthe video recorder to the source program signal. The second comparingmeans compares the signal from the video recorder to the signal acquiredby the television receiver signal acquiring means.

In accordance with yet a further aspect of the present invention, amethod of determining the source of a signal selected for use by a userat a monitored receiver in a household comprises the steps of: (a)selecting, by means of a source receiver, a source signal correspondingto a channel; (b) acquiring, by use of a non-intrusive sensor disposedproximate to the monitored receiver, a representation of the signalselected by the user; (c) comparing the representation of the signalselected by the user to the source signal in order to determine adifference between the representation and the source signal; (d) if thedifference is less than a predetermined amount, identifying therepresentation as the source signal; (e) if the difference is not lessthan a predetermined amount, controlling the source receiver to receivea source signal-corresponding to another channel and repeating steps (c)and (d).

In accordance with a still further aspect of the present invention, amethod of reading an ancillary code operably associated with a userselected program signal transmitted from one of a plurality of programchannels to which a household receiver in a household is tuned comprisesthe steps of: (a) acquiring the user selected program signal from thehousehold receiver; (b) acquiring a source program signal from apredetermined one of the plurality of program channels; (c) comparingthe source program signal to the user selected program signal and, ifthe source program signal and the user selected program signal differ byless than a predetermined amount, reading the ancillary code from thesource program signal.

In accordance with another aspect of the present invention, a method ofidentifying which of first and second signal sources is supplying aprogram signal to a monitored receiver, wherein the first and secondsignal sources and the monitored receiver are located in a household,comprises to following steps: (a) comparing a sync signal from an outputof one of the first and second signal sources to a sync signal from anoutput of the monitored receiver; (b) if the sync signal from an outputof one of the first and second signal sources matches the sync signalfrom an output of the monitored receiver, extracting a reference programsignature representative of the output of the monitored receiver and asignature representative of the output of the one of the first andsecond signal sources; (c) identifying which of the first and secondsignal sources is a source of the program signal if the referenceprogram signature and the signature representative of the output of theone of the first and second signal sources match; and (d) if the syncsignal from an output of the one of the first and second signal sourcesdoes not match the sync signal from an output of the monitored receiver,comparing a sync signal from an output of another of the first andsecond signal sources to a sync signal from an output of the monitoredreceiver and repeating steps (b) and (c) as necessary.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic illustration showing the components of a prior arttelevision audience measurement system which is improved by the presentinvention;

FIG. 2 illustrates in greater detail the statistically selectedhousehold of FIG. 1 as measured in accordance with the prior art;

FIG. 3 is a schematic block diagram of a preferred embodiment of thepresent invention; and,

FIG. 4 is a state table summarizing VCR measurements which may be madeusing the apparatus of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A television audience measurement system 10 of the sort taught by Thomaset al. in U.S. Pat. No. 5,481,294 is depicted schematically in FIG. 1.Programs transmitted from a plurality of program transmitters 12 (whichare depicted in the drawing as over-the-air transmitters, but which mayinclude any transmitter of program signals such as CATV, directsatellite broadcast, and/or the like) are received at a statisticallyselected household 14. The same program signals from the same programtransmitters 12 are also received by a local monitoring site 16.Generally, although not necessarily, the local monitoring site 16 of thetelevision audience measurement system 10 is located in a correspondingregional market being measured, and serves a plurality of statisticallyselected households, such as the statistically selected household 14,which are located within that regional market. All such statisticallyselected households communicate their data to a central site 18.

Also, there may be a plurality of regional markets each having acorresponding local monitoring site 16 and each local monitoring site 16serving a plurality of corresponding statistically selected households14. All such statistically selected households and all such localmonitoring sites communicate their data to the central site 18.

Data, which may comprise identifying ancillary codes transmitted withthe programs transmitted by the program transmitters 12, or which maycomprise program signatures characteristic of such programs, areextracted from the received transmitted programs by both thestatistically selected household 14 and the local monitoring site 16,and the extracted data are sent from both the statistically selectedhousehold 14 and the local monitoring site 16 to the central site 18.The central site 18 compiles television audience reports based upon thisdata from the statistically selected household 14 and the localmonitoring site 16 as well as from all other statistically selectedhouseholds located within the receiving area of the local monitoringsite 16, from all other statistically selected households located withinthe receiving areas of all other corresponding local monitoring sites,and from all other local monitoring sites.

In general accordance with the teachings of Thomas et al. in U.S. Pat.No. 5,481,294, the portion of the television audience measurement system10 located within the statistically selected household 14 is shown inmore detail in FIG. 2. As shown therein, the program transmitters 12transmit RF program signals to a signal input 20, which is generallyshown as an antenna but which may be any other type of program signalinput, such as a cable input, a satellite dish, and/or the like. Theprogram signals received by the signal input 20 may comprise a pluralityof channels of television programming and are routed to one or moretelevision receivers 22, 22′ of the statistically selected household 14.

Each of the television receivers 22, 22′ may have associated with it acorresponding local (i.e., non-transmitted) video signal source 24, 24′.For example, the local video signal source 24 associated with thetelevision receiver 22 may be a video game 26, and the local videosignal source 24′ associated with the television receiver 22′ may be aVCR 28. The local video signal sources 24, 24′ may be configured to sendtheir output video signals to their corresponding television receivers22, 22′.

Non-invasive signal sensors 30, such as microphones, photodetectors,inductive pickups, and/or the like, are arranged, and are located, toacquire representations of the program signals selected for viewing onthe television receiver 22. These representations are preprocessed by apreprocessing circuit 32 in a manner, for example, described in theaforementioned U.S. Pat. No. 5,481,294. The preprocessed representationsare passed to a code reader 34 and to a signature extractor 36. The codereader 34 and the signature extractor 36 produce program identifyingdata from the preprocessed representations. Thus, for example, the codereader 34 reads ancillary codes from the preprocessed representations,and the signature extractor 36 extracts signatures from the preprocessedrepresentations.

The program identifying data extracted by the code reader 34 and thesignature extractor 36 are sent to a data storage and telecommunicationprocessor 38 for subsequent transmission by way of a transmission medium40 to the central site 18. Also, as is well known in the art, a localclock 42 associated with the data storage and telecommunicationprocessor 38 is conventionally synchronized with a master clock at thecentral site 18 whenever data are transferred between the statisticallyselected household 14 and the central site 18 over the transmissionmedium 40. The transmission medium 40, for example, may be the publicswitched telephone network.

Similarly, non-invasive signal sensors 30′ are arranged, and arelocated, to acquire representations of the program signals selected forviewing on the television receiver 22′. These representations arepreprocessed by a preprocessing circuit 32′. The preprocessedrepresentations are passed to a code reader 34′ and to a signatureextractor 36′. The code reader 34′ and the signature extractor 36′produce program identifying data from the preprocessed representations.Thus, for example, the code reader 34′ reads ancillary codes from thepreprocessed representations, and the signature extractor 36′ extractssignatures from the preprocessed representations. The programidentifying data read by the code reader 34′ and extracted by thesignature extractor 36′ are sent to the data storage andtelecommunication processor 38 for subsequent transmission to thecentral site 18.

A people meter 43 may also be associated with the television receiver22. The people meter 43 may be any of the people meters used by NielsenMedia Research, Inc. to meter the viewing habits of panelists, andgenerally determines the channel being viewed and the identities of theviewers of the television receiver 22. Also, a people meter 43′ may beassociated with the television receiver 22′. The people meter 43′ may besimilar to the people meter 43.

FIG. 3 illustrates a program signal source detector 44 which may be usedfor the portion of the television audience measurement system 10 locatedwithin the statistically selected household 14 as shown in FIG. 2 andwhich is suitable for accurately determining a local source of signals,such as the VCR 28, being displayed on a monitored television, such asthe television receiver 22′. If desired, the local metering site 16 maybe eliminated. However, the local metering site 16 may be desirable inthose markets where no one statistically selected household receives allof the possible signals that are available in the market in which thestatistically selected household 14.

As shown in FIG. 3, a signal input 46, which is generally shown asan-antenna but which may be any program signal input, such as a cableinput, a satellite dish, and/or the like, receives the program signalstransmitted by the program transmitters 12. The program signals receivedby the signal input 46 may comprise a plurality of channels oftelevision programming. The program signals received by the signal input46 may be split by a splitter 48 so as to be fed to both householdentertainment equipment 50 and a channel selection apparatus 52. Itshould be noted here that, in determining the local source of videoand/or audio being displayed by the television receiver 22′, the outputof the television receiver 22′ is the reference signal, and the outputof the channel selection apparatus 52, the game 26, the VCR 28, etc. isthe source signal. The household entertainment equipment 50 and thechannel selection apparatus 52 are located within the statisticallyselected household 14. As is known, a user of the householdentertainment equipment 50 may choose from among many variousinterconnections in order to route a selected signal to a televisionand/or other equipment. In the interest of clarity of presentation,however, these various interconnections, which may be made by the user,are not shown in FIG. 3.

In some cases, the selected signal is routed through the VCR 28 and thensupplied to its associated television receiver 22′. This routing iscommonly done at RF via a suitable cable from an RF output of the VCR 28to an RF input of the television receiver 22′, but the signal may alsobe supplied to the television receiver 22′ as a baseband audio signalfrom a VCR baseband audio output of the VCR 28 and/or as a basebandvideo signal from a VCR baseband video output of the VCR 28. Forpurposes of the program signal source detector 44, however, a VCR audiooutput 56 of the VCR 28 may be a baseband audio output of the VCR 28,and a VCR video output 58 of the VCR 28 may be a baseband video outputof the VCR 28.

In one mode of operation of the VCR 28, hereinafter called the “TVmode,” the RF signals from the signal input 46 are supplied directly tothe television receiver 22′, and the VCR 28 is not involved in thetuning process. The VCR 28 is in this mode whenever it is unpowered. Inanother mode, hereinafter called “VCR TUNE,” a tuner within the VCR 28is used to select one of the plurality of program signals received bythe signal input 46 and to supply that selected signal as an output ofthe VCR 28 to its television receiver 22′. In a further mode,hereinafter called “PLAY,” a signal stored on a video cassette (or tape)is supplied by the VCR 28 to its television receiver 22′. In yet afurther mode, hereinafter called “RECORD,” a program signal is recordedby the VCR 28 for later, time shifted viewing.

When the VCR 28 is in the RECORD mode, its erase head is powered so asto erase whatever old signal may be on the cassette (or tape) before thenew signal is recorded. The operation of the erase head can be detectedby finding some artifact of the erase head tone. As noted by Vitt et al.in U.S. Pat. No. 5,165,069, this detection may be done in a non-invasivemanner with an inductive sensor installed adjacent to the VCR 28. Italso has been also found that an artifact of the erase head signal canoften be detected directly from the VCR audio output 56 of some modelsof the VCR 28. The manner of detecting the erase head signal depends onthe specific model of the VCR 28 being monitored. If an artifact of theerase head signal cannot be detected directly from the VCR audio output56 of the VCR 28, the program signal source detector 44 may employ aninput from a radiated signal pickup (not shown) of the sort disclosed byVitt et al.

As shown in FIG. 3, three of the non-invasive signal sensors 30′ areemployed to acquire-representations of various signal components fromthe television receiver 22′ whenever it is turned on. These threenon-invasive signal sensors may include (i) a suitable sync signalpickup 60 which may be of the type disclosed in copending applicationSer. No. 08/654,309 filed on May 28, 1996, which is disposed adjacentthe television receiver 22′, and which picks up a representation of thevertical and horizontal synchronization pulses of the televisionreceiver 22′, (ii) a video signal pickup 62 which may be of the typedisclosed in the aforementioned copending application Ser. No.08/654,309 filed on May 28, 1996 and which is arranged to pick up arepresentation of the video signal being displayed by the televisionreceiver 22′, and (iii) an audio signal pickup 64, which may be amicrophone as taught by Thomas et al. in U.S. Pat. No. 5,481,294 andwhich is used to acquire the audio portion of the displayed programsignal for subsequent matching operations.

It is noted that the video signal pickup 62 may not, and probably doesnot, acquire the full video signal (some attenuation at the higherfrequencies and the lowest frequencies is common), but the failure ofthe video signal pickup 62 to acquire the full video signal is of noparticular concern in the overall measurement system of the presentinvention because the matching operations disclosed hereinafter can beconducted using only mid-frequency components of the various videosignals. It is also noted that the video signal pickup 62 may not, andprobably does not, acquire the information contained in the verticalblanking interval of the video signal because the video signal pickup 62is preferably located near the CRT of the television receiver 22′ andbecause the vertical blanking interval is commonly not supplied to theCRT video of the television receiver 22′. Accordingly, ancillary codeslocated in the vertical blanking interval cannot be read from the outputof the video signal pickup 62. It will be understood to those skilled inthe art that both the video signal pickup 62 and the audio signal pickup64 may employ appropriate circuitry (not separately shown) to matchtheir output levels to the industry standard output levels of thesignals obtained from the VCR video output 58 and the VCR audio output56 against which they are matched.

If the television receiver 22′ is a television model provided with anexternal video jack, such an external video jack can be used in lieu ofthe video signal pickup 62 and the sync signal pickup 60. Similarly, ifthe television receiver 22′ is a television model provided with anexternal audio jack, such an external audio jack can be used in lieu ofthe audio signal pickup 64.

The channel selection apparatus 52 of the program signal source detector44 employs a source scanning tuner 66. The source scanning tuner 66 hasaccess to the signal input 46 by means of the splitter 48 and may scanall of the available programming channels under control of a controller68. The controller 68 may be a PIC 16c65 that is slaved to a digitalsignal processor 70 (which may be a Texas Instrument model TMS320C32-60) of a digital signal processing module 71. The digital signalprocessor 70 may be considered to have a signature extraction portion70′ and a signature correlating portion 70″. The source scanning tuner66 provides a video output 72 and one or two audio outputs 74 and 9 (thesecond of these being associated with a Secondary Audio Program (SAP)signal component of some television transmissions) that are subsequentlyused in matching operations in order to determine the source of thesignals displayed on the television receiver 22′.

As depicted in FIG. 3, the program signal source detector 44 is capableof (i) extracting an audio program signature from a program signal, (ii)extracting a video program signature from the program signal, (iii)extracting an audio ancillary code from the program signal, and (iv)extracting a video ancillary code from the program signal. Any one ormore of these detection functions may be used in order to identify thelocal source of the signals displayed by the television receiver 22′.For example, the tuner of the television receiver 22′ may be identifiedas the source of the signals being displayed by the television receiver22′ if a reference audio signature extracted from an audio output of thetelevision receiver 22′, matches a source audio signature extracted froman audio output of the source scanning tuner 66 or if a reference videosignature extracted from a video output of the television receiver 22′matches a source video signature extracted from a video output of thesource scanning tuner 66.

Similarly, the VCR 28 may be identified as the local source of thesignals being displayed by the television receiver 22′ if a referenceaudio signature extracted from an audio output of the televisionreceiver 22′ matches a source audio signature extracted from an audiooutput of the VCR 28 or if a reference video signature extracted from avideo output of the television receiver 22′ matches a source videosignature extracted from a video output of the VCR 28, the game 26 maybe identified as the local source of the signals being displayed by thetelevision receiver 22′ if a reference audio signature extracted from anaudio output of the television receiver 22′ matches a source audiosignature extracted from an audio output of the game 26 or if areference video signature extracted from a video output of thetelevision receiver 22′ matches a source video signature extracted froma video output of the game 26, and so on.

The channel selection apparatus 52 may receive a plurality of RF programsignals in addition to the RF program signals received by the signalinput 46. For example, these other program signals may include off-airchannels received by an antenna other than the antenna 46, channelsreceived by way of a CATV cable (which may be received directly, orwhich may be received through a cable converter), channels received by asatellite dish, and/or the like. The program signals received by thesignal input 46 and the other program signals described above areconnected through RF multiplexers 80 to the input of the source scanningtuner 66 under control of the controller 68.

The video output 72 from the source scanning tuner 66 is applied to botha source video multiplexer 82 and a reference video multiplexer 84,while the audio output 74 and the second audio program (SAP) output 9from the source scanning tuner 66 are applied to both a source audiomultiplexer 86 and a reference audio multiplexer 88. Also applied toboth the source video multiplexer 82 and the reference video multiplexer84 are (i) the VCR video output 58 from the VCR 28, (ii) a video output90 from the video game 26, (iii) a VCR video output 92 from a second VCR94 which might also be used with the television receiver 22′, (iv) avideo output 96 from a Direct Broadcast Satellite receiver 98, and (v) avideo output 100 from the television receiver 22′. Similarly, applied toboth the source audio multiplexer 86 and the reference audio multiplexer88 are (i) the VCR audio output 56 from the VCR 28, (ii) an audio output102 from the video game 26, (iii) a VCR audio output 104 from the secondVCR 94, (iv) an audio output 106 from the Direct Broadcast Satellitereceiver 98, and (v) an audio output 108 from the television receiver22′. The source video multiplexer 82, the reference video multiplexer84, the source audio multiplexer 86, and the reference audio multiplexer88 comprise an input multiplexer module 110. Additionally, the videosignal pickup 62 is applied to the source video multiplexer 82 and tothe reference video multiplexer 84, and the audio signal pickup 64 isapplied to the source audio multiplexer 86 and to the reference audiomultiplexer 88.

The output from the source video multiplexer 82 is connected through avideo signal conditioner circuit 111 and a multiplexer 112 to one inputof a digitizer 114′ and then to the signature extraction portion 70′ ofthe digital signal processor 70. Similarly, the output from thereference video multiplexer 84 is connected through a video signalconditioner circuit 113 and a multiplexer 118 to one input of thedigitizer 114′ and then to the signature extraction portion 70′ of thedigital signal processor 70. The signature extraction portion 70′,similarly to the signature extractor 36 of FIG. 2, extracts videoprogram signatures from signals on selected ones of the inputs of thesource video multiplexer 82 and the reference video multiplexer 84.Accordingly, the signature correlation portion 70″ may correlatesreference video signatures extracted from a video output of thetelevision receiver 22′ to source video signatures extracted from avideo output of the game 26, a video output of the VCR 28, a videooutput of the source scanning tuner 66, a video output of the second VCR94, and/or a video output of the Direct Broadcast Satellite receiver 98,in order to determine whether the tuner of the television receiver 22′,the game 26, the VCR 28, the second VCR 94, or the Direct BroadcastSatellite receiver 98 is the source of the signals being displayed bythe television receiver 22′.

The output from the source video multiplexer 82 is also connecteddirectly through the multiplexer 112 and the digitizer 114′ to a codereader 114″. Similarly, the output from the reference video multiplexer84 is also connected directly through the multiplexer 118 and thedigitizer 114′ to the code reader 114″. The code reader 114″ may besimilar to the code reader 34 of FIG. 2. The code reader 114″ extractsan ancillary code from a signal on a selected one of the inputs of thesource video multiplexer 82 and/or on a selected one of the inputs ofthe reference video multiplexer 84.

The output from the source audio multiplexer 86 is connected through themultiplexer 112 to one input of the digitizer 114′ and then to thesignature extraction portion 70′ of the digital signal processor 70.Similarly, the output from the reference audio multiplexer 88 isconnected through the multiplexer 118 to one input of the digitizer 114′and then to the signature extraction portion 70′ of the digital signalprocessor 70. The signature extraction portion 70′ extracts audioprogram signatures from signals on selected ones of the inputs of thesource audio multiplexer 86 and the reference audio multiplexer 88.Accordingly, the signature correlation portion 70″ may correlatesreference audio signatures extracted from an audio output of thetelevision receiver 22′ to source audio signatures extracted from anaudio output of the game 26, an audio output of the VCR 28, an audiooutput of the source scanning tuner 66, an audio output of the secondVCR 94, and/or an audio output of the Direct Broadcast Satellitereceiver 98, in order to determine whether the tuner of the televisionreceiver 22′, the game 26, the VCR 28, the second VCR 94, or the DirectBroadcast Satellite receiver 98 is the source of the signals beingdisplayed by the television receiver 22′.

The output from the source audio multiplexer 86 is also connecteddirectly through the multiplexer 112 and the digitizer 114′ to the codereader 114″. Similarly, the output from the reference audio multiplexer88 is also connected directly through the multiplexer 118 and thedigitizer 114′ to the code reader 114″. The code reader 114″ extracts anancillary code from a signal on a selected one of the inputs of thesource audio multiplexer 86 and/or on a selected one of the inputs ofthe reference audio multiplexer 88.

The output from the reference video multiplexer 84 is also connected toa sync matching circuit 116 which compares the standard sync signal assensed by the sync signal pickup 60 with the sync signals derived fromthe signal on a selected one of the inputs of the reference videomultiplexer 84. The sync matching circuit 116 passes a match between thestandard sync signal as sensed by the sync signal pickup 60 and a syncsignal derived from the signal on a selected one of the inputs of thereference video multiplexer 84 to the digital signal processing module71.

With this arrangement, a reference video signature extracted from avideo output of the television receiver 22′ may be compared to sourcevideo signatures extracted from a video output of the game 26, a videooutput of the VCR 28, a video output of the source scanning tuner 66, avideo output of the second VCR 94, a video output of the DirectBroadcast Satellite receiver 98, and the like in order to determine thelocal source of the signals displayed by the television receiver 22′.Alternatively or in addition, a reference audio signature extracted froman audio output of the television receiver 22′ may be compared to sourceaudio signatures extracted from an audio output of the game 26, an audiooutput of the VCR 28, an audio output of the source scanning tuner 66,an audio output of the second VCR 94, an audio output of the DirectBroadcast Satellite receiver 98, and the like in order to determine thelocal source of the signals displayed by the television receiver 22′.

Because the correlation of signatures is computationally expensive, thedigital signal processing module 71 may first control the referencevideo multiplexer 84 in order to pass the video signal on the videooutput 72 of the source scanning tuner 66 to the sync matching circuit116 which matches suitable synchronization components of the videooutput of the source scanning tuner 66 and from the sync signal pickup60. Until a match is found, the controller 68 causes the source scanningtuner 66 to sequentially tune to the possible signal sources.

When a match between synchronization components is found, the digitalsignal processing module 71 controls the source video multiplexer 82 inorder to pass the video signal currently on the video output 72 of thesource scanning tuner 66 to the video signal conditioner circuit 111,the multiplexer 112, and the signature extraction portion 70′, and thedigital signal processing module 71 controls the reference videomultiplexer 84 in order to pass the video signal on the video output 100(or 67) of the television receiver 22′ to the video signal conditionercircuit 113, the multiplexer 118, and the signature extraction portion70′. (The video signal conditioner circuit 113 is always bypassed whenusing the video signal from the video signal pickup 62.) The signatureextraction portion 70′ and the signature correlating portion 70″ of thedigital signal processor 70 extracts and correlates video signaturesfrom the video signal corresponding to the channel selected by thesource scanning tuner 66 and the video signal corresponding to a channelselected by the television receiver 22′. These channels are the channelsthat are in sync as determined by the sync matching circuit 116. If amatch is not found, it may be concluded that the sync tested by the syncmatching circuit 116 relates to different channels. Accordingly, thecontroller 68 steps the source scanning tuner 66 to the next channel torestart the process of finding synchronization and, if synchronizationis found, of extracting and comparing video signatures. If a match ofvideo signatures is found, the tuner of the television receiver 22′ isidentified as the local source of the signals displayed by thetelevision receiver 22′.

Alternatively, when a match between synchronization components is found,the digital signal processing module 71 controls the source audiomultiplexer 86 in order to pass the audio signal on the audio output 74of the source scanning tuner 66 to the multiplexer 112 and the signatureextraction portion 70′, and the digital signal processing module 71 maycontrol the reference audio multiplexer 88 in order to pass the audiosignal on the audio output 108 (or the audio signal pickup 64) of thetelevision receiver 22′ to the multiplexer 118 and the signatureextraction portion 70′. The signature extraction portion 70′ and thesignature correlating portion 70″ of the digital signal processor 70extracts and correlates audio signatures from the audio signalcorresponding to the channel selected by the source scanning tuner 66and the audio signal corresponding to a channel selected by thetelevision receiver 22′. These channels are the channels that are insync as determined by the sync matching circuit 116. If a match is notfound, it may be concluded that the sync found by the sync matchingcircuit 116 relates to different channels. Accordingly, the controller68 steps the source scanning tuner 66 to the next channel to restart theprocess of finding synchronization and, if synchronization is found, ofextracting and comparing audio signatures. If a match of audiosignatures is found, the tuner of the television receiver 22′ isidentified as the local source of the signals displayed by thetelevision receiver 22′.

After a match is thus found, the identity of this signal source may beconfirmed by reading an ancillary code, if present, from the videosignal on the video output 72 of the source scanning tuner 66. It shouldbe noted here that, if the video signal pickup 62 is used to derive avideo signal from the television receiver 22′, and if ancillary codesare inserted in the vertical blanking interval of video signals, theancillary code cannot be read from the video signal on the video signalpickup 62 because, in many modern television sets, the vertical blankinginterval is not present in video signal at the point where the videosignal pickup 62 picks up the video signal. Accordingly, ancillary codescan instead be read from the video output 72 of the source scanningtuner 66 when the source scanning tuner 66 is tuned to the channel towhich the television receiver 22′ is tuned. However, if the video output100 is used to derive a video signal from the television receiver 22′,if the video output 100 is at baseband, and if ancillary codes areinserted in the vertical blanking interval of video signals, theancillary code can be read from the video signal on the video output 100because the vertical blanking interval is present in the baseband videosignal. Alternatively, the identity of this signal source may beconfirmed by reading an ancillary code, if present, from the audiosignal on the audio output 74 of the source scanning tuner 66 or on theaudio output 108 (or 64) of the television receiver 22′.

If signatures extracted from all of the channels to which the sourcescanning tuner 66 may be tuned do not match signatures extracted fromthe output of the television receiver 22′, reference video and/or audiosignatures extracted from a video and/or audio output of the televisionreceiver 22′ may be compared to source video and/or audio signaturesextracted from a video and/or audio output of the game 26, from a videoand/or an audio output of the VCR 28, from a video and/or an audiooutput of the second VCR 94, from a video and/or an audio output of theDirect Broadcast Satellite receiver 98, and the like in a similar mannerin order to determine whether any of these local sources is the localsource of the signals displayed by the television receiver 22′.

Also, various modes of the VCR 28 (and of the second VCR 94) can bedetermined by the arrangement of the present invention. FIG. 4 disclosesin table form the operation of the present invention in order to monitorthe modes of a VCR. As shown in FIG. 4, if the erase head of the VCR 28is active, if the outputs of the VCR 28 and of the source scanning tuner66 match, and if the outputs of the VCR 28 and of the televisionreceiver 22′ match, then it may be concluded that the VCR 28 is in theRECORD mode and that the program being recorded is also being viewed atthe same time.

The operation of the erase head of the VCR 28 can be detected by thedigital signal processing module 71 from a VCR erase detector 119 whichis associated with the VCR 28. (Also, a VCR erase detector 120 may beassociated with the second VCR 94.) The erase head detector 119 may beof the sort disclosed by Vitt et al. Alternatively, the code reader 114may be arranged to-detect an artifact of the erase signal of the VCR 28from the VCR audio output 56 of the VCR 28 by use of either the sourceaudio multiplexer 86 or the reference audio multiplexer 88.

In order to determine if the outputs of the VCR 28 and of the sourcescanning tuner 66 match, the video outputs of the VCR 28 and of thesource scanning tuner 66 may be correlated. For example, the digitalsignal processing module 71 may control the source video multiplexer 82in order to pass the video signal on the video output 72 to the videosignal conditioner circuit 11, the multiplexer 112, and the signatureextraction portion 70′, and the digital signal processing module 71 maycontrol the reference video multiplexer 84 in order to pass the videosignal on the VCR video output 58 to the video signal conditionercircuit 113, the multiplexer 118, and the signature extraction portion70′. The signature extraction portion 70′ and the signature correlatingportion 70″ of the digital signal processor 70 extracts and correlatesvideo signatures from a video signal corresponding to a channel selectedby the source scanning tuner 66 and from a video signal corresponding toa channel selected by the VCR 28. If these video signatures do notmatch, the controller 68 may step the source scanning tuner 66 througheach of the channels until a match is found.

Alternatively, the digital signal processing module 71 may control thesource audio multiplexer 86 in order to pass the audio signal on theaudio output 74 to the multiplexer 112 and the signature extractionportion 70′, and the digital signal processing module 71 may control thereference audio multiplexer 88 in order to pass the audio signal on theVCR audio output 56 to the multiplexer 118 and the signature extractionportion 70′. The signature extraction portion 70′ and the signaturecorrelating portion 70″ of the digital signal processor 70 extracts andcorrelates audio signatures from the audio signal corresponding to achannel selected by the source scanning tuner 66 and from the audiosignal corresponding to a channel selected by the VCR 28. If these audiosignatures do not match, the controller 68 may step the source scanningtuner 66 through each of the channels until a match is found.

In order to determine if the outputs of the VCR 28 and of the televisionreceiver 22′ match, the video outputs of the VCR 28 and of thetelevision receiver 22′ may be correlated. The correlation of theoutputs of the VCR 28 and of the television receiver 22′ also can bedetermined by the digital signal processing module 71. For example, thedigital signal processing module 71 may control the source videomultiplexer 82 in order to pass the video signal on the video output 100from the television receiver 22′ to the video signal conditioner circuit11, the multiplexer 112, and the signature extraction portion 70′, andthe digital signal processing module 71 may control the reference videomultiplexer 84 in order to pass the video signal on the video output 58of the VCR 28 to the video signal conditioner circuit 113, themultiplexer 118, and the signature extraction portion 70′. The signatureextraction portion 70′ and the signature correlating portion 70″ of thedigital signal processor 70 extracts and correlates video signaturesfrom the video signal corresponding to a channel selected by the VCR 28and the video signal corresponding to a channel selected by thetelevision receiver 22′.

Alternatively, the digital signal processing module 71 may control thesource audio multiplexer 86 in order to pass the audio signal on theaudio output 108 from the television receiver 22′ to the multiplexer 112and the signature extraction portion 70′, and the digital signalprocessing module 71 may control the reference audio multiplexer 88 inorder to pass the audio signal on the audio output 56 of the VCR 28 tothe multiplexer 118 and the signature extraction portion 70′. Thesignature extraction portion 701 and the signature correlating portion70″ of the digital signal processor 70 extracts and correlates audiosignatures from the audio signal corresponding to a channel selected bythe VCR 28 and the audio signal corresponding to a channel selected bythe television receiver 22′.

If the television receiver 22′ does not have output jacks so that thevideo output 100 and the audio output 108 are not present and so thatthe video signal pickup 62 and the audio signal pickup 64 are insteadused to sense the video and audio signals of the television receiver22′, signatures from the video signals on the video output 58 of the VCR28 and on the video signal pickup 62 of the television receiver 22′ maybe correlated in the manner described above, or signatures from theaudio signals on the audio output 56 of the VCR 28 and on the audiosignal pickup 64 of the television receiver 22′ may be correlated in themanner described above.

As also shown in FIG. 4, if the erase head of the VCR 28 is active, ifthe outputs of the VCR 28 and of the source scanning tuner 66 match, andif the outputs of the VCR 28 and of the television receiver 22′ do notmatch, then it may be concluded that the VCR 28 is in the RECORD mode,but that the program being recorded is not also being viewed on thetelevision receiver 22′ at the same time. The operation of the erasehead of the VCR 28 can be detected as described above, the outputs ofthe VCR 28 and of the source scanning tuner 66 can be correlated asdescribed above in order to determine that they match, and the outputsof the VCR 28 and of the television receiver 22′ can be correlated asdescribed above in order to determine that they do not match.

As shown in FIG. 4, if the erase head of the VCR 28 is not active, ifthe outputs of the VCR 28 and of the source scanning tuner 66 do notmatch, and if the outputs of the VCR 28 and of the television receiver22′ do match, then it may be concluded that the VCR 28 is in the PLAYmode. The operation of the erase head of the VCR 28 can be detected asdescribed above, the outputs of the VCR 28 and of the source scanningtuner 66 can be correlated as described above in order to determine thatthey do not match, and the outputs of the VCR 28 and of the televisionreceiver 22′ can be correlated as described above in order to determinethat they do match.

Again as shown in FIG. 4, if the erase head of the VCR 28 is not active,if the outputs of the VCR 28 and of the source scanning tuner 66 match,and if the outputs of the VCR 28 and of the television receiver 22′match, then it may be concluded that the VCR 28 is not recording orplaying, but is instead being used to tune the television receiver 22′,to fast forward a cassette (or tape), or to rewind a cassette (or tape).The use of the VCR 28 as a tuner may be credited by the program signalsource detector 44. The operation of the erase head of the VCR 28 can bedetected as described above, the outputs of the VCR 28 and of the sourcescanning tuner 66 can be correlated as described above in order todetermine that they match, and the outputs of the VCR 28 and of thetelevision receiver 22′ can be correlated as described above in order todetermine that they match.

As finally shown in FIG. 4, if the erase head of the VCR 28 is notactive, if the outputs of the VCR 28 and of the source scanning tuner 66do not match, and if the outputs of the VCR 28 and of the televisionreceiver 22′ also do not match, then it may be concluded that the VCR 28is off. The operation of the erase head of the VCR 28 can be detected asdescribed above, the outputs of the VCR 28 and of the source scanningtuner 66 can be correlated as described above in order to determine thatthey do not match, and the outputs of the VCR 28 and of the televisionreceiver 22′ can be correlated as described above in order to determinethat they do not match. The digital signal processing module 71 maydetermine the on or off state of the television receiver 22′ bydetecting the presence or loss of a sync signal on the sync signalpickup 60.

Also, the arrangement of FIG. 3 may be used to identify programs beingplayed by the VCR 28 or being displayed by the television receiver 22′.For example, video and/or audio program identifying ancillary codescontained in the program signal being recorded by the VCR 28 may be readby the code correlating portion 114″ and may be stored in a memory ofthe digital signal processing module 71. The stored video and/or audioprogram identifying ancillary codes can be compared with those read bythe code correlating portion 114″ during the subsequent PLAY mode of theVCR 28 in order to determine if and when the recorded program signal isplayed back. The video and/or audio program identifying ancillary codesread by the code correlating portion 114″ during either the RECORD modeor the subsequent PLAY mode of the VCR 28 may also be used to identifythe programs being played in accordance with the teachings of theaforementioned U.S. Pat. No. 5,481,294.

If video and/or audio program identifying ancillary codes are notpresent in the signals being recorded and/or played, characteristicvideo and/or audio program signatures of the program signal beingrecorded by the VCR 28 may be extracted by the signature extractionportion 70′ and may be stored in the-memory of the digital signalprocessing module 71. The stored characteristic video and/or audiosignatures can be compared by the signature correlating portion 70″ withthose extracted by the signature extraction portion 70′ during asubsequent PLAY mode in order to determine if and when the recordedprogram signal is played back. If a match is found, the signaturesextracted during play or recording may be compared to known signaturespreviously extracted from known programs by the local metering site 16or by the source scanning tuner 66 in order to identify the recordedand/or played program in accordance with the teachings of theaforementioned U.S. Pat. No. 5,481,294.

Similarly, video and/or audio program identifying ancillary codes of aprogram signal tuned by the tuner of the television receiver 22′ may beread by the code correlating portion 114″ at the video and/or audiooutputs of the television receiver 22′. The video and/or audio programidentifying ancillary codes may be used to identify the programsdisplayed by the television receiver 22′ in accordance with theteachings of the aforementioned U.S. Pat. No. 5,481,294. If video and/oraudio program identifying ancillary codes are not present in the signalsat the output of the television receiver 22′, characteristic videoand/or audio program signatures of the program signal at the output ofthe television receiver 22′ may be extracted by the signature extractionportion 70′. These signatures may be compared to known signaturespreviously extracted from known programs by the local metering site 16or by the source scanning tuner 66 in order to identify the displayedprogram in accordance with the teachings of the aforementioned U.S. Pat.No. 5,481,294.

Programs being recorded and/or played by the second VCR 94, games fromthe video game 26 being displayed by the television receiver 22′, andprograms from the Direct Broadcast Satellite receiver 98 being displayedby the television receiver 22′, may be similarly identified through theuse of program identifying ancillary codes and characteristic programsignatures. It should be noted, however, that the playing of rented orpurchased cassettes (or tapes) is often more common than playing backtime-shifted, previously recorded programs. Accordingly, it is expectedthat most attempts to use characteristic program signatures in order toidentify programs being played on the VCR 28 will fail to yield anidentifying match. However, program identifying ancillary codes arefrequently added to pre-recorded cassettes (or tapes) so that, in thosecases, the program signal source detector 44 installed in thestatistically selected household 14 will still be able to identify theprogram being played by the VCR 28.

Certain modifications of the present invention have been discussedabove. Other modifications will occur to those practicing in the art ofthe present invention. For example, although the present invention hasbeen specifically described in connection with a television audiencemeasurement system, the present invention may be used in connection withother systems such as program verification systems.

Also, although the present invention has been described in connectionwith the monitoring of television receivers, the present invention maybe used in connection with the monitoring of other receivers, such asradio receivers.

Similarly, although the present invention has been described inconnection with monitoring VCRs, the present invention may be used inconnection with monitoring other recording and/or playing equipment suchas disk players, audio cassette and disk recorders/players, and thelike, and in connection with signal sources that are less complex thanVCRs and like equipment.

Moreover, as described above, the signature correlating portion 70″ ofthe digital signal processor 70 and the code correlating portion 114″ ofthe code reader 114 are located in the statistically selected household14. However, the signature correlating portion 70″ and the codecorrelating portion 114″ instead may be located in the central site 18.

Furthermore, as described above, signatures are extracted from an outputof the television receiver 22′ and from an output of a local source ofprogram signals, and these signatures are correlated in order toidentify the source as the source of the signals being displayed by thetelevision receiver 22′. These signatures may be exact analog or digitalrepresentations of the relevant programs signals so that the output ofthe television receiver 22′ and the output of a source to be identifiedas the source of the program signals being displayed by the televisionreceiver 22′ may be directly correlated either in analog form or indigital form without the necessity of sampling the program signals.Alternatively, the signatures may be sampled representations of therelevant programs signals.

Accordingly, the description of the present invention is to be construedas illustrative only and is for the purpose of teaching those skilled inthe art the best mode of carrying out the invention. The details may bevaried substantially without departing from the spirit of the invention,and the exclusive use of all modifications which are within the scope ofthe appended claims is reserved.

1. An apparatus for determining an operating mode of a recording/playingdevice comprising: an extractor to extract signatures associated with afirst signal associated with a tuner that is to tune to a programsignal, a second signal associated with a recording/playing device thatis to at least one of record or play a program, and a third signalassociated with a receiver coupled to the recording/playing device; arecording detector to detect a recording signal generated by therecording/playing device during recording of the program to form arecorded program; a correlator to correlate the first, second, and thirdsignals; and a processor to identify the operating mode of therecording/playing device based on detection of the recording signal andcorrelation of two or more of the first, second or third signals.
 2. Anapparatus as defined in claim 1, wherein the processor is to identify arecord mode associated with the recording/playing device in response tothe recording detector detecting the recording signal and the correlatordetecting that the first signal matches the second signal.
 3. Anapparatus as defined in claim 1, wherein the processor is to identifythat the recorded program is received by the receiver in response to thecorrelator detecting that the second signal matches the third signal. 4.An apparatus as defined in claim 1, wherein the processor is to identifythat the recorded program is not received by the receiver in response tothe correlator detecting that the second signal does not match the thirdsignal.
 5. An apparatus as defined in claim 1, wherein the processor isto identify at least one of a play mode, a tune mode, a fast forwardmode, a rewind mode, an off mode or a receiver operating mode associatedwith the recording/playing device in response to the recording detectorfailing to detect the recording signal.
 6. An apparatus as defined inclaim 5, wherein the processor is to identify the play mode in responseto the correlator detecting that the first signal does not match thesecond signal, and that the second signal matches the third signal. 7.An apparatus as defined in claim 5, wherein the processor is to identifyat least one of the tune mode, the fast forward mode or the rewind modein response to the correlator detecting that the first signal matchesthe second signal, and that the second signal matches the third signal.8. An apparatus as defined in claim 5, wherein the tune mode comprises amode associated with the recording/playing device tuning the receiver.9. An apparatus as defined in claim 5, wherein the processor is toidentify at least one of the off mode or the receiver operating mode inresponse to detecting that the first signal does not match the secondsignal, and that the second signal does not match the third signal. 10.An apparatus as defined in claim 1 further comprising a non-invasivesensor to detect at least one of the second and third signals or therecording signal.
 11. An apparatus as defined in claim 10, wherein thenon-invasive sensor comprises at least one of a microphone, aphotodetector, and an inductive pickup.
 12. An apparatus as defined inclaim 1, wherein the signatures comprise at least one of a videosignature and an audio signature.
 13. An apparatus as defined in claim1, wherein the recording signal comprises an erase head signal.
 14. Anapparatus as defined in claim 1, wherein the recording/playing devicecomprises at least one of a video cassette recorder/player, a compactdisc recorder/player, a digital video disc recorder/player or an audiocassette recorder/player.
 15. An apparatus as defined in claim 1,wherein the receiver comprises at least one of a television receiver ora radio receiver.
 16. A method for determining an operating mode of arecording/playing device comprising: extracting signatures associatedwith a first signal associated with a tuner that is to tune to a programsignal, a second signal associated with a recording/playing device thatis to at least one of record or play a program, and a third signalassociated with a receiver coupled to the recording/playing device;detecting a recording signal generated by the recording/playing deviceduring recording of the program to form a recorded program; correlatingthe first, second, and third signals; and using a processor to identifythe operating mode of the recording/playing device based on detection ofthe recording signal and correlation of two or more of the first, secondor third signals.
 17. A method as defined in claim 16 further comprisingidentifying a record mode associated with the recording/playing devicein response to detecting the recording signal and detecting that thefirst signal matches the second signal.
 18. A method as defined in claim16 further comprising identifying that the recorded program is receivedby the receiver in response to detecting that the second signal matchesthe third signal.
 19. A method as defined in claim 16 further comprisingidentifying that the recorded program is not received by the receiver inresponse to detecting that the second signal does not match the thirdsignal.
 20. A method as defined in claim 16 further comprisingidentifying at least one of a play mode, a tune mode, a fast forwardmode, a rewind mode, an off mode or a receiver operating mode associatedwith the recording/playing device in response to failing to detect therecording signal.
 21. A method as defined in claim 20, whereinidentifying the play mode occurs in response to detecting that the firstsignal does not match the second signal, and that the second signalmatches the third signal.
 22. A method as defined in claim 20, whereinidentifying at least one of the tune mode, the fast forward mode or therewind mode occurs in response detecting that the first signal matchesthe second signal, and that the second signal matches the third signal.23. A method as defined in claim 20, wherein the tune mode comprises amode associated with the recording/playing device tuning the receiver.24. A method as defined in claim 20, wherein the identifying at leastone of the off mode or the receiver operating mode occurs response todetecting that the first signal does not match the second signal, andthat the second signal does not match the third signal.
 25. A method asdefined in claim 16 wherein the detecting of at least one of the secondand third signals or the recording signal occurs via at least one of amicrophone, a photodetector or an inductive pickup.
 26. A method asdefined in claim 16, wherein the signatures comprise at least one of avideo signature or an audio signature.
 27. A method as defined in claim16, wherein the recording signal comprises an erase head signal.
 28. Amethod as defined in claim 16, wherein the recording/playing devicecomprises at least one of a video cassette recorder/player, a compactdisc recorder/player, a digital video disc recorder/player or an audiocassette recorder/player.
 29. A method as defined in claim 16, whereinthe receiver comprises at least one of a television receiver or a radioreceiver.
 30. A machine readable medium having instructions storedthereon, which when executed, cause a machine to determine an operatingmode of a recording/playing device by causing the machine to: extractsignatures associated with a first signal associated with a tuner thatis to tune to a program signal, a second signal associated with arecording/playing device that is to at least one of record or play aprogram, and a third signal associated with a receiver coupled to therecording/playing device; detect a recording signal generated by therecording/playing device during recording of the program to form arecorded program; correlate the first, second, and third signals; andidentify the operating mode of the recording/playing device based ondetection of the recording signal and correlation of two or more of thefirst, second or third signals.
 31. A machine readable medium as definedclaim 30 that has instructions stored thereon, which when executed,cause a machine to identify a record mode associated with therecording/playing device in response to detecting the recording signaland detecting that the first signal matches the second signal.
 32. Amachine readable medium as defined claim 30 that has instructions storedthereon, which when executed, cause a machine to identify that therecorded program is received by the receiver in response to detectingthat the second signal matches the third signal.
 33. A machine readablemedium as defined claim 30 that has instructions stored thereon, whichwhen executed, cause a machine to identify that the recorded program isnot received by the receiver in response to detecting that the secondsignal does not match the third signal.
 34. A machine readable medium asdefined claim 30 that has instructions stored thereon, which whenexecuted, cause a machine to identify at least one of a play mode, atune mode, a fast forward mode, a rewind mode, an off mode or a receiveroperating mode associated with the recording/playing device in responseto failing to detect the recording signal.
 35. A machine readable mediumas defined claim 34, wherein the machine is to identify the play mode inresponse to detecting that the first signal does not match the secondsignal, and that the second signal matches the third signal.
 36. Amachine readable medium as defined claim 34, wherein the machine is toidentify at least one of the tune mode, the fast forward mode or therewind mode in response detecting that the first signal matches thesecond signal, and that the second signal matches the third signal. 37.A machine readable medium as defined claim 34, wherein the machine is toidentify at least one of the off mode or the receiver operating mode inresponse to detecting that the first signal does not match the secondsignal, and that the second signal does not match the third signal. 38.A machine readable medium as defined claim 30, wherein the signaturescomprise at least one of a video signature or an audio signature.